/*
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0
 
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/


#include "ts_lua_util.h"


static int ts_lua_transform_handler(TSCont contp, ts_lua_http_transform_ctx *transform_ctx, TSEvent event, int n);


int
ts_lua_transform_entry(TSCont contp, TSEvent ev, void *edata)
{
    int                         n, event;
    TSVIO                       input_vio;
    ts_lua_http_transform_ctx	*transform_ctx;

    event = (int)ev;
    transform_ctx = (ts_lua_http_transform_ctx*)TSContDataGet(contp);

    if (TSVConnClosedGet(contp)) {
        ts_lua_destroy_http_transform_ctx(transform_ctx);
        return 0;
    }

    n = 0;

    switch (event) {

        case TS_EVENT_ERROR:
            input_vio = TSVConnWriteVIOGet(contp);
            TSContCall(TSVIOContGet(input_vio), TS_EVENT_ERROR, input_vio);
            break;

        case TS_EVENT_VCONN_WRITE_COMPLETE:
            TSVConnShutdown(TSTransformOutputVConnGet(contp), 0, 1);
            break;

        case TS_LUA_EVENT_COROUTINE_CONT:
            n = (intptr_t)edata;

        case TS_EVENT_VCONN_WRITE_READY:
        default:
            ts_lua_transform_handler(contp, transform_ctx, event, n);
            break;
    }

    return 0;
}

static int
ts_lua_transform_handler(TSCont contp, ts_lua_http_transform_ctx *transform_ctx, TSEvent event, int n)
{
    TSVConn                 output_conn;
    TSVIO                   input_vio;
    TSIOBufferReader        input_reader;
    TSIOBufferBlock         blk;
    int64_t                 toread, towrite, blk_len, upstream_done, input_avail, l;
    const char              *start;
    const char              *res;
    size_t                  res_len;
    int                     ret, eos, write_down, rc, top;
    ts_lua_coroutine        *crt;
    ts_lua_cont_info        *ci;

    lua_State               *L;
    TSMutex                 mtxp;

    ci = &transform_ctx->cinfo;
    crt = &ci->routine;

    mtxp = crt->mctx->mutexp;
    L = crt->lua;

    output_conn = TSTransformOutputVConnGet(contp);
    input_vio = TSVConnWriteVIOGet(contp);

    if (!TSVIOBufferGet(input_vio)) {
        if (transform_ctx->output.vio) {
            TSVIONBytesSet(transform_ctx->output.vio, transform_ctx->total);
            TSVIOReenable(transform_ctx->output.vio);
        }

        return 0;
    }

    input_reader = TSVIOReaderGet(input_vio);

    if (!transform_ctx->output.buffer) {
        transform_ctx->output.buffer = TSIOBufferCreate();
        transform_ctx->output.reader = TSIOBufferReaderAlloc(transform_ctx->output.buffer);

        transform_ctx->reserved.buffer = TSIOBufferCreate();
        transform_ctx->reserved.reader = TSIOBufferReaderAlloc(transform_ctx->reserved.buffer);

        transform_ctx->upstream_bytes = TSVIONBytesGet(input_vio);
        transform_ctx->downstream_bytes = INT64_MAX;
    }

    input_avail = TSIOBufferReaderAvail(input_reader);
    upstream_done = TSVIONDoneGet(input_vio);
    toread = TSVIONTodoGet(input_vio);

    if (toread <= input_avail) {        // upstream finished
        eos = 1;

    } else {
        eos = 0;
    }

    if (input_avail > 0) {
        // move to the reserved.buffer
        TSIOBufferCopy(transform_ctx->reserved.buffer, input_reader, input_avail, 0);

        // reset input
        TSIOBufferReaderConsume(input_reader, input_avail);
        TSVIONDoneSet(input_vio, upstream_done + input_avail);
    }

    write_down = 0;
    towrite = TSIOBufferReaderAvail(transform_ctx->reserved.reader);

    TSMutexLock(mtxp);
    ts_lua_set_cont_info(L, ci);

    do {
        if (event == TS_LUA_EVENT_COROUTINE_CONT) {
            event = 0;
            goto launch;

        } else {
            n = 2;
        }
 
        if (towrite == 0)
            break;

        blk = TSIOBufferReaderStart(transform_ctx->reserved.reader);
        start = TSIOBufferBlockReadStart(blk, transform_ctx->reserved.reader, &blk_len);

        lua_pushlightuserdata(L, transform_ctx);
        lua_rawget(L, LUA_GLOBALSINDEX);                    /* push function */

        if (towrite > blk_len) {
            lua_pushlstring(L, start, (size_t)blk_len);
            towrite -= blk_len;
            TSIOBufferReaderConsume(transform_ctx->reserved.reader, blk_len);

        } else {
            lua_pushlstring(L, start, (size_t)towrite);
            TSIOBufferReaderConsume(transform_ctx->reserved.reader, towrite);
            towrite = 0;
        }

        if (!towrite && eos) {
            lua_pushinteger(L, 1);                          /* second param, data finished */ 

        } else {
            lua_pushinteger(L, 0);                          /* second param, data not finish */ 
        }

launch:
        rc = lua_resume(L, n);
        top = lua_gettop(L);

        switch (rc) {
            case LUA_YIELD:         // coroutine yield
                TSMutexUnlock(mtxp);
                return 0;

            case 0:                 // coroutine success
                if (top == 2) {
                    ret = lua_tointeger(L, -1);             /* 0 is not finished, 1 is finished */
                    res = lua_tolstring(L, -2, &res_len);

                } else {            // what hells code are you writing ?
                    ret = 0;
                    res = NULL;
                    res_len = 0;
                }

                break;

            default:                // coroutine failed
                ee("lua_resume failed: %s", lua_tostring(L, -1));
                ret = 1;
                res = NULL;
                res_len = 0;
                break;
        }

        if (res && res_len > 0) {
            if (!transform_ctx->output.vio) {
                l = transform_ctx->downstream_bytes;
                if (ret)
                    l = res_len;

                transform_ctx->output.vio = TSVConnWrite(output_conn, contp, transform_ctx->output.reader, l);      // HttpSM go on
            }

            TSIOBufferWrite(transform_ctx->output.buffer, res, res_len);
            transform_ctx->total += res_len;
            write_down = 1;
        }

        lua_pop(L, top);

        if (ret || (eos && !towrite)) {            // EOS
            eos = 1;
            break;
        }

    } while (towrite > 0);

    TSMutexUnlock(mtxp);

    if (eos && !transform_ctx->output.vio)
        transform_ctx->output.vio = TSVConnWrite(output_conn, contp, transform_ctx->output.reader, 0);

    if (write_down || eos)
        TSVIOReenable(transform_ctx->output.vio);

    if (toread > input_avail) {     // upstream not finished.
        if (eos) {
            TSVIONBytesSet(transform_ctx->output.vio, transform_ctx->total);
            TSContCall(TSVIOContGet(input_vio), TS_EVENT_VCONN_EOS, input_vio);

        } else {
            TSContCall(TSVIOContGet(input_vio), TS_EVENT_VCONN_WRITE_READY, input_vio);
        }

    } else {                        // upstream is finished.
        TSVIONBytesSet(transform_ctx->output.vio, transform_ctx->total);
        TSContCall(TSVIOContGet(input_vio), TS_EVENT_VCONN_WRITE_COMPLETE, input_vio);
    }

    return 0;
}
